Re: Huff-Puff Stabilizer

Hans Summers <Hans.Summers@...>
 

Hi Troy

On my Huff & Puff web page:
http://www.hanssummers.com/radio/huffpuff/index.htm I have a complete .pdf
library of all the articles I have been able to find about Huff & Puff
stabilisers, going back over 30 years.

Earlier this year I designed some minimalist versions of existing
stabilisers, see
http://www.hanssummers.com/radio/huffpuff/minimalist/index.htm . At the
frequency you speak of, the "fast" stabiliser is probably overkill. So I'd
recommend a simple 2-chip stabiliser such as you will see on that page,
using a cheap 32.768kHz watch crystal as reference oscillator. The 1-chip
version is even more minimalist but I designed that more as a challenge and
a technical curiosity, rather than as a really sensible design: it is
workable but it is harder to adjust than the 2-chip design and is less
efficient. Arv K7HKL has even had it working on a 14MHz VFO though!

If you are using a FET LC oscillator you will need a buffer transistor
amplifier to get the signal to a level suitable for digital logic. I use the
single transistor buffer shown in my SPRAT article see
http://www.hanssummers.com/radio/huffpuff/library/sprat123.pdf .

Another interesting possibility which I have been discussing with Alan
RW3RQT concerns using the spare D-type flip flop as a buffer amplifier.
Consider that in the 2-chip design I connected that D-type flip flop to
behave as an inverter gate. If you bias an inverter gate to its linear
region by connecting a resistor (e.g. 100K) from its output to its input, it
can behave as an amplifier. Look for example at U1a in the QRP2001 radio,
bottom left of the circuit diagram:
http://www.qrp2001.freeserve.co.uk/qrp2001rf.gif . So, when using an
external VFO (not half the 74hc74), then a spare D-type is available which
could be made into an inverter, and perhaps turned into an input
amplifier... It would be cool to be able to reduce the parts count by
eliminating the transistor buffer amplifier!

73 Hans G0UPL

-----Original Message-----
From: kc8afu1965 [mailto:kc8afu1965@...]
Sent: 20 September 2005 15:12
To: BITX20@...
Subject: [BITX20] Huff-Puff Stabilizer


Hello,

I have been monitoring this group on and off for about a year. I am
looking for some suggestions on a huff-puff stabilizer that I can use
for a Homebrew CW transceiver. My VFO is a FET LC oscillator that runs
at 2.6 - 2.7 MHz (approximately). I am looking for something that
will work automatically ( I understand that there are designs in which
you need to tell the correction to go higher or lower in freq). Also I
am hoping for something that will work with RIT. Oh, by the way I
really don't understand how they work. They Look a lot like a PLL to
me, But I don't understand the Difference. I don't fully understand
PLLs either.

Any ideas.

Troy






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